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Disclaimer: I'm sorry if you have to read this, wikispaces hates me, so it messed my fonts and formatting up. SORRY!!!! :'(   **__The Electromagnetic Spectrum__**

Humans have been curious about our world since the dawn of our time. Our collective curiosity has led us to endless discoveries. One of the most startling discoveries that humanity has found was the electromagnetic spectrum. This is one discovery in particular that has been a wonderful collaboration between scientists all over the world and over several hundred years. The spectrum was the discovery of many great scientists and philosophers, from Ptolemy to Isaac Newton. While the project is a testament to collaboration, it is mainly a spectacular scientific discovery that we expand upon every day and can apply to our world in a very straightforward manner.

**__Vocabulary and Definitions__** Electromagnetic radiation is a topic that is very difficult to understand without knowing the definitions of a few words that will be used frequently in this paper. The following definitions should make this research paper easier to understand. The study of light and the perception of the human eye is called optics. This field began in ancient Greece around 300 BC and has yielded hundreds of discoveries since, including the existence of something known as the electromagnetic spectrum. This spectrum is everywhere in the world and therefore understanding it makes it much easier to understand the rest of the world.

A spectrum is a range of components used for classification in which the components are arranged according to one characteristic they all have. The rainbow, for example, is a spectrum of visible light from red to violet with a specific order based on one of their shared qualities, their color. The electromagnetic spectrum, the topic of this research paper, is a range of waves that contain heat and light as two of its main components. This particular spectrum also contains other waves that I will discuss later. A wave is defined as a motion within matter that can travel from one place to another through that matter. There are two main types of waves, transverse and longitudinal, but this paper will only describe transverse waves.

**__Types of Radiation__**

Within the electromagnetic spectrum, there are several different types of radiation arranged by the wavelength they have, or how long the wave travels before it reaches the same point in its path as when the measurement started. The wave with the longest wavelength, at more than 10 cm according to NASA, is the microwave. After the microwave comes the radio wave, with a slightly shorter wavelength and therefore a bit more power. After those two come in frared radiation, which is the type of radiation that produces heat. The sun also produces this type of radiation. Next on the spectrum is visible light, a type of radiation that comes in many colors and is the only type that can be seen by the human eye without outside assistance. Ultraviolet waves come next, and with their diminished wavelength, they are the first ones that can injure a human. These types of waves cause sunburns and can lead to skin cancer. X-Rays are the next ones on the spectrum. They are very helpful in the medical field but when used excessively can be harmful to us, and cause certain kinds of cancer. Gamma rays are the most mysterious wavelength of the entire spectrum because they are blocked by our atmosphere. However, we do know that they can be very harmful to humans.

**__Discovery Timeline__** The discovery of the electromagnetic spectrum was spread out over hundreds of years. The scientists who studied it are some of the best recognized in their fields. The discoveries all started with the field of optics in ancient Greece in approximately 300 BC. Then, during the second century AD, a man from Alexandria named Ptolemy published five books on the study of optics, only one of which has survived to the present day. In 1000 AD Alhazan, also called Abu Ali Hasan Ibn al-Haitham, conducted the first serious study on lenses and refraction. The same man also went on to study spherical and parabolic mirrors and was the first person to correctly conjecture that light comes to our eyes instead of coming out of them.

Later on in the 13th century, Roger Bacon correctly guessed that a rainbow is just light refracted through raindrops in the air. However, he could not prove this. The next breakthrough came in 1665 when Isaac Newton studied refraction through prisms. He proved that a prism was only splitting up white light into its component colors instead of adding colors as many believed. He also showed that the prism process was reversible, therefore finding the visible part of the spectrum. In 1740, William Herschel discovered the infrared part of the spectrum by measuring the temperature of different wavelengths that came out of a prism. Soon after in 1800, Johann Ritter wanted to see what was after violet on the spectrum and found ultraviolet light by exposing silver chloride to different parts of the spectrum and watching for violent reactions.

**__Applications__** Each of these types of radiation is very real and present in the lives of human beings. Radio waves produce the AM and FM signals that all radio stations use. Microwaves are the power behind the microwave ovens that exist in most American homes today. Infrared waves are contained in sunlight and keep the planet warm and humanity alive. Visible light makes it possible for us to see the world around us. It was this type of light that began the search for knowledge about the electromagnetic spectrum, and therefore led to its discovery.

The ultraviolet wavelength on the spectrum is also contained in common sunlight. This type of radiation is the kind that causes sunburn on human skin. Labels saying “UV protection” can be seen on most sunglasses because this radiation is occasionally also harmful to human eyes. X-rays are used most in the medical field, although they have also begun their use as security devices very recently. These rays are very harmful to the unprotected human body, and therefore lead coats are often worn when in proximity to X-ray scanners.

The electromagnetic spectrum is everywhere in our world, from the things we buy to the equipment we see in the doctor’s office. This discovery has been monumental in figuring out how we see and experience the world. The field of optics has interested us for generations; the spectrum interested the greatest minds in science our world has ever seen and yet it is simple enough to be taught in classrooms around the country. The Electromagnetic Spectrum embodies this sort of elegance we look for in the world, and I hope that I have shown at least a piece of that in my writing.

**__Bibliography__** __The Electromagnetic Spectrum__. Writ., Dir., and Prod. The Bonus Point Band. Online Video. TeacherTube, 2010.

Branley, Franklin M. __The Electromagnetic Spectrum: Key to the Universe__. Thomas Y. Crowell, 1979.

Volkmann, Walter H. __Electromagnetic Spectrum: New Many Speeds Theory__. Flower Mound: Taylor Publishing Co., 2008

“Electromagnetic Spectrum.” NASA Home Page. 3 Feb. 2010, [|http://imagine.gsfc.nasa.gov/docs/science/know_|1/emspectrum.html] (2 Dec. 2010) Amigos School Computer Lab.

__Electromagnetic Turkey__. Writ., Prod. Chris Williams, Dir. Alice Dallow. Television. Discovery Channel, 2009.

Julian Rubin, “The Discovery of the Spectrum of Light.” Following the Path of Discovery. Oct., 2010, [] (15 Dec. 2010) Cambridge Massachusetts.

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